The present invention relates to a method for the fabrication of capacitor and, more particularly, to a method for fabricating a capacitor that is capable of reducing defects incurred during the separation of capacitor.
FIGS. 1A to 1C are schematic cross-sectional views illustrating a prior art method for the fabrication of capacitor.
As shown in FIGS. 1A, an interlayer insulating film 12 is disposed on a semiconductor substrate 11 obtained by a predetermined process, followed by the deposition of an interlayer insulating film 12 that is selectively etched to form a contact hole for a storage node of the capacitor. Next, a conductive layer is disposed on the whole surface including the contact hole, and a storage node contact plug 13 is formed using an etchback process or a chemical-mechanical polishing (CMP) process. Wherein the storage node contact plug 13 is connected to the semiconductor substrate 11 through the contact hole and has a double layered structure.
In an ensuing step, a capacitor oxidation film 14 is formed on the whole surface, including the storage node contact plug 13, and a mask for defining the capacitor is then formed thereon. Subsequently, the capacitor oxidation film 14 is selectively etched using the mask to thereby expose a portion on which a bottom electrode of the capacitor is to be formed (i.e., a portion to which the storage node contact plug 13 is exposed). Thereafter, the interlayer insulating film 12 and the capacitor oxidation film 14 in a peripheral circuit region II are selectively etched to form an alignment key box pattern 15.
After the above step, a polysilicon layer 16, for the bottom electrode is formed on the whole surface including the exposed portion. A mask 17 is disposed thereon through the use of a photosensitive film serving to expose the peripheral circuit region II.
As shown in FIG. 1B, the polysilicon 16 in the peripheral circuit region II is etched using the mask 17, after which a distinct bottom electrode 16a is formed using the CMP process. In this case, a photosensitive film 17a remains within the contact hole in the bottom electrode 16a. 
As shown in FIG. 1C, the photosensitive film 17a remaining within the bottom electrode 16a is then removed.
The prior art method suffers from a drawback, in that, it employs the chemical mechanical polishing process for the separation of the capacitors, resulting in an excessive height loss of the capacitor and various defects resulting from various causes, e.g., slurry residue, broken portions of the capacitor structure, dishing, and particles, which, in turn, deteriorates the yield of the resulting semiconductor device.
In addition, the prior art method must utilize four distinct pieces of equipment such as equipment for removal of the polysilicon in the peripheral circuit region II, equipment for the chemical-mechanical polishing, equipment for stripping away the photosensitive film and equipment for the wet etch. As a result of the need for these various pieces of equipment and the associated handling, the prior art process suffers from a shortcoming in that it increases the number of defect sources and increases the process time, both of which tend to deteriorate the yield of semiconductor device.
It is, therefore, a primary object of the present invention to provide a method for fabricating capacitors that is capable of reducing defects introduced as the result of the complicated process during the separation of capacitor, to thereby enhance the yield of the resulting semiconductor device.
In accordance with a preferred embodiment of the present invention, there is provided a method for the fabrication of capacitor, comprising the steps of: forming an insulating film on a semiconductor substrate in which a cell region and a peripheral circuit region are defined; selectively etching the insulating film, followed by opening a region in which a bottom electrode will be formed; depositing a conductive layer for the bottom electrode on the whole surface, including the opened region; forming a photosensitive film pattern that exposes the peripheral circuit region; removing the conductive layer in the peripheral circuit region using the photosensitive film as a mask; applying an etchback process to the photosensitive film to expose the conductive layer in the cell region; applying an etchback process to the conductive layer until the insulating film covered with the conductive layer is exposed, to thereby form a distinct bottom electrode; and stripping away the remaining photosensitive film.